This is the final installment for a while in my journal detailing my repair of a used Oscar espresso machine I picked up for parts or repair. After cleaning everything inside and out and searching out and eliminating all the leaks, I still could not get the machine to work properly. Electronically the machine is fine - the temperature responds to adjustments to the pressurestat, the pump fills the boiler properly, it steams like nothing I have ever seen, but it cannot pull a shot without causing the boiler release safety valve to open.
I can actually pull a shot like this with a rag wrapped around the pressure release on top of the boiler. most of what is expressed from the boiler is steam so very little water condenses to dampen the rag. The shots even taste good. This is so very bitter sweet though. I know I am so close to having a working Oscar. After some trouble shooting I have determined that he heat exchange tube inside the boiler has developed a crack. This is not that uncommon if the machine was stored in a sub freezing environment with water still in the tube. Some place like Upstate New York might be cold enough in the winter.
Unlike a professional machine, the heat exchange tube is not replaceable. This unit needs a new boiler to be repaired unless I find the time to locate a welder to silver solder a patch if possible. If the tube is too damaged I might try stuffing another tube or pipe inside of the existing heat exchange and fix it so it threads into the pipes leading to the group. Right now my desire to repair the Oscar is low so the project is on the back burner. After buying my new Quick Mill Silvano from ROASTe I am not feeling very pushed. Both are very nice machines but one is new so the one needing mending can wait.
Knowing I can eventually get the Oscar up and running played a big part in my choosing the Silvano too - not many people get the opportunity to play around with a pair of thousand dollar espresso machines but before long I will be able to do just that. I will keep this updated but it will likely be after Christmas before I have the spare time - If I get it working sooner I will update that too.